Some vehicle systems, such as trains, can include multiple vehicles coupled with each other by couplers. During movement of these vehicle systems, the couplers may be exposed to various forces. For example, the vehicles in the vehicle system may compress and/or pull on the couplers and cause the couplers to experience compressive and tensile forces at various locations during travel of the vehicle system.
Large increases or changes in these forces can impair handling of the vehicle system and/or damage the couplers. In order to reduce the forces, some known systems can restrict or otherwise modify throttle notch positions during a trip of the vehicle system. For example, while the vehicle system may have the capability of changing a throttle notch position between values of negative eight to eight, a system may prevent the vehicle system from increasing the throttle notch position above a value of four (or another value) in an attempt to prevent the forces on the couplers from being too large. Other systems can prevent the throttle notch positions from changing too rapidly. For example, these systems can prevent automatic and/or manual changes in the throttle notch position from occurring too frequently in an attempt to prevent the forces on the couplers from being too large. Some other systems can identify throttle notch positions that are expected to reduce the forces exerted on the couplers and use these throttle notch positions during travel of the vehicle system.
These approaches to reducing the forces exerted on the couplers, however, may not be sufficiently effective. This is particularly noticeable for vehicle systems with have a relatively small amount of power relative to other environmental forces (e.g., grade) such as freight trains. Another approach to reducing the forces exerted on the couplers includes reliance on a manual determination of an operator of when or where to change throttle notch positions. This determination may largely be based on the experience of the operator and, as a result, can be prone to human error.